The OverPass Chill App needs to be open at all times to collect data from the Chill tags. However, when you are on the phone, texting or on another app, the iOS App will not collect location data. When you are finished with that other activity, please bring the OverPass Chill App to the foreground to continue to capture all temperature and location data in real-time. If your phone restarts by a user action or from a dead battery, the OverPass Chill App does not start up automatically and will need to be restarted.
The other reason for not capturing location data is the Chill Tag may be out of range from the iPhone.
All temperature data is stored on the Tag and is read when the App is opened or within range of the Tag either in real time or from memory. No Temperature data is ever lost.